Humidity control systems are conventionally known that control the humidity of a room by adsorbing and desorbing moisture in air.
For example, Patent Document 1 discloses a humidity control system including a refrigerant circuit in which adsorption heat exchangers each carrying an adsorbent thereon are connected. In the refrigerant circuit of the humidity control system, a compressor, a first adsorption heat exchanger, an expansion valve, a second adsorption heat exchanger and a four-way selector valve are connected. The refrigerant circuit operates in a refrigeration cycle by circulating refrigerant therethrough. Out of the two adsorption heat exchangers, one serves as an evaporator and the other serves as a condenser. The adsorption heat exchanger serving as an evaporator performs an adsorption action of adsorbing moisture in air to the adsorbent, while the adsorption heat exchanger serving as a condenser performs a regeneration action of releasing moisture in the adsorbent to air.
Specifically, during a humidification operation of the humidity control system, outdoor air passes through the adsorption heat exchanger serving as a condenser. In this adsorption heat exchanger, the adsorbent is heated by the refrigerant and moisture is thereby desorbed from the adsorbent and released to the outdoor air. The air humidified by this regeneration action is supplied as supply air to a room to humidify the room. On the other hand, room air passes through the adsorption heat exchanger serving as an evaporator. In this adsorption heat exchanger, the adsorbent is cooled by the refrigerant and moisture in the air is thereby adsorbed to the adsorbent. The air having given moisture to the adsorbent by this adsorption action is exhausted as exhaust air to the outside.
Furthermore, during a dehumidification operation of the humidity control system, outdoor air passes through the adsorption heat exchanger serving as an evaporator. In this adsorption heat exchanger, the adsorbent is cooled by the refrigerant and moisture in the air is thereby adsorbed to the adsorbent. The air dehumidified by this adsorption action is supplied as supply air to the room to dehumidify the room. On the other hand, room air passes through the adsorption heat exchanger serving as a condenser. In this adsorption heat exchanger, the adsorbent is heated by the refrigerant and moisture is thereby desorbed from the adsorbent and released to the air. The air used for regeneration of the adsorbent by this regeneration action is exhausted as exhaust air to the outside.
In this humidity control system, the regeneration action and the adsorption action are alternately repeated in each of the two adsorption heat exchangers by switching the air flow path with dampers and concurrently switching the direction of refrigerant circulation in the refrigerant circuit with the four-way selector valve. Thus, according to this humidity control system, humidity-controlled air is continuously supplied to the room without impairing the adsorption and regeneration capacities of the adsorbents.    Patent Document 1: Published Japanese Patent Application No. 2004-294048